American Board of Ophthalmology (ABO) Practice Exam 2025 – The Complete All-in-One Guide to Exam Success

The eyepiece on a lensometer serves the essential function of allowing the user to focus the light to achieve a clear view of the markings on the lens being measured. When using a lensometer, the light passes through the lens, and the eyepiece is adjusted to ensure that the examiner can see the image accurately. Proper focusing through the eyepiece is crucial for obtaining precise lens measurements, as it enables the user to interpret the optical properties of the lens correctly.

Each of the other functions mentioned is linked to different components of the lensometer. For instance, measuring curvature pertains more to the lens being assessed rather than the eyepiece itself. Calibration of the device usually involves adjustments separate from the eyepiece, ensuring the measurements are accurate over time. Adjusting the lens mounting is also a mechanical function that deals with how the lens is placed in the machine for measurement, rather than focusing the light through the eyepiece. Thus, the primary role of the eyepiece revolves around achieving a sharp and clear view to facilitate accurate lens evaluation.